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The crawler-transporters are a pair of tracked vehicles used to transport spacecraft from NASA's Vehicle Assembly Building (VAB) along the Crawlerway to Launch Complex 39. They were originally used to transport the Saturn IB and Saturn V rockets during the Apollo, Skylab and Apollo–Soyuz programs. They were then used to transport Space Shuttles from 1981 to 2011. The crawler-transporters carry vehicles on the Mobile Launcher Platform, and after each launch return to the pad to take the platform back to the VAB. The two crawler-transporters were designed and built by Marion Power Shovel using components designed and built by Rockwell International at a cost of each. Upon its construction, the crawler-transporter became the largest self-powered land vehicle in the world. While other vehicles such as bucket-wheel excavators like Bagger 288 are significantly larger, they are powered by external sources. ==Specifications== The crawler-transporter has a mass of and has eight tracks, two on each corner. Each track has 57 shoes, and each shoe weighs . The vehicle measures . The height from ground level to the platform is adjustable from , and each side can be raised and lowered independently of the other. The crawler uses a laser guidance system and a leveling system to keep the Mobile Launcher Platform level within 10 minutes of arc (about at the top of the Saturn V), while moving up the 5% grade to the launch site. A separate laser docking system provides pinpoint accuracy when the crawler-transporter and Mobile Launch Platform are positioned in the VAB or at the launch pad. A team of nearly 30 engineers, technicians and drivers operate the vehicle. The crawlers were overhauled in 2003 with upgrades to the Motor Control Center, which houses the switchgear and electrical controls of all of major systems on board, a new engine and pump ventilation system and new diesel engine radiators, and replacement of the two driver cabs on each vehicle (one on each end).〔 As of 2003, each crawler had 16 traction motors, powered by four generators, in turn driven by two V16 ALCO 251C diesel engines. Two generators, driven by two engines, were used for jacking, steering, lighting, and ventilating. Two generators were also available to power the Mobile Launcher Platform. The crawler's tanks held of diesel fuel, and it burned .〔 Due to its age and the need to support the heavier Space Launch System and its launch tower, in mid-2012 one of the crawlers was undergoing an upgrade involving "new engines, new exhausts, new brakes, new hydraulics, new computers," to increase its lifting capacity from .〔 The crawler is controlled from two control cabs located at either end of the vehicle, and travels along the crawlerway at a maximum speed of loaded, or unloaded. The average trip time from the VAB along the Crawlerway to Launch Complex 39 is about five hours.〔 Each crawlerway is deep and covered with Alabama and Tennessee river rock for its low friction properties to reduce the possibility of sparks. In 2000, NASA unearthed and restored an Apollo-era segment of the crawlerway to provide access to a high-bay building in order to provide protection from a hurricane. Kennedy Space Center has been using the same two crawlers, now nicknamed "Hans" and "Franz", since their initial delivery in 1965. In their lifetime, they have traveled more than , about the same driving distance as from Miami to Seattle.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Crawler-transporter」の詳細全文を読む スポンサード リンク
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